1. Field of the Invention
The invention relates to a flat panel display, and in particular to a flat panel display and a backlight module thereof.
2. Description of the Related Art
Flexible printed circuit board (FPCB) is widely used in electronic devices for electrical connection requiring elasticity and light weight, enabling internal space of electronics to be effectively utilized and convenient to assemble.
FIG. 1 is a schematic view of a conventional backlight 10 for a flat panel display. The conventional backlight 10 comprises a frame 11, a flexible printed circuit board 12, a light source (not shown), and other elements. The flexible printed circuit board 12 is generally long and thin, and disposed on a front side F′ of the backlight module 10. A portion of the flexible printed circuit board 12 protrudes from the frame 11, connecting to other circuit boards in the flat panel display, providing signal transfer and power to a light source. Additionally, signals transmitted by or received from the backlight module 10 are transmitted via the flexible printed circuit board 12 to other interfaces of the flat panel display. Two conventional connection methods frequently used to connect the flexible printed circuit board and other circuit boards of the flat panel display are shown in FIGS. 2A and 2B, respectively.
FIG. 2A is a side view of an assembly of a printed circuit board 15 and a backlight module 10 of a conventional flat panel display 100. FIG. 2B is a side view of another assembly of a printed circuit board 15 and a backlight module 10 of the conventional flat panel display 100.
As shown in FIG. 2A, the flat panel display 100 comprises a printed circuit board 15 and a backlight module 10 disposed thereon. A flexible printed circuit board 12 for light source protrudes from the frame of the backlight module 10 and connects to the printed circuit board 15 via a connector 16.
The disadvantage of the design is that connector 16, having large volume, requires additional space, and thus, the connector 16 occupies most usable space on the circuit board 15 or the flexible circuit board 12. The connector must be assembled manually, whereby labor time and costs cannot be effectively controlled.
FIG. 2B is a schematic view of a flexible printed circuit board 12 for light source, welded to bare copper (not shown) of another printed circuit board 15 of a flat panel display by solder 17. In this method, since connectors are eliminated, material costs are reduced, but assembly time and costs cannot. Welding quality depends on skill and performance and can vary with the parameters of pressure welding, machines, and thickness of solder. Thus, connection quality is difficult to control. If the product must be repaired or reassembled, the flexible printed circuit board can possibly overheat, deform, or even break such that the product is irreparable. If assembly fails, materials are wasted, increasing assembly time, and assembly costs cannot be effectively controlled.
Note that, since the flexible printed circuit board protrudes from the frame to connect to an external circuit, strength of the frame is not strong enough, and when the frame is compromised, display quality of the flat panel is affected accordingly.